package com.icesoft.wechat.utils.decode;

import lombok.SneakyThrows;

import java.security.MessageDigest;
import java.util.Arrays;

@SuppressWarnings("unused")
public class WxSHA1 {
	/*
	 * 微信公众平台(JAVA) SDK
	 *
	 * Copyright (c) 2016, Ansitech Network Technology Co.,Ltd All rights reserved.
	 * http://www.ansitech.com/weixin/sdk/
	 *
	 * Licensed under the Apache License, Version 2.0 (the "License");
	 * you may not use this file except in compliance with the License.
	 * You may obtain a copy of the License at
	 *
	 *   http://www.apache.org/licenses/LICENSE-2.0
	 *
	 * Unless required by applicable law or agreed to in writing, software
	 * distributed under the License is distributed on an "AS IS" BASIS,
	 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	 * See the License for the specific language governing permissions and
	 * limitations under the License.
	 */

	/**
	 * <p>Title: SHA1算法</p>
	 *
	 * @author levi
	 */

	private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5',
			'6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

	/**
	 * 用SHA1算法生成安全签名
	 *
	 * @param token     票据
	 * @param timestamp 时间戳
	 * @param nonce     随机字符串
	 * @return 安全签名
	 */
	@SneakyThrows
	public static String getSHA1(String token, String timestamp, String nonce) {
		String[] array = new String[]{token, timestamp, nonce};
		StringBuffer sb = new StringBuffer();
		// 字符串排序
		Arrays.sort(array);
		for (String s : array) {
			sb.append(s);
		}
		String str = sb.toString();
		return encode(str);
	}

	/**
	 * Takes the raw bytes from the digest and formats them correct.
	 *
	 * @param bytes the raw bytes from the digest.
	 * @return the formatted bytes.
	 */
	private static String getFormattedText(byte[] bytes) {
		int len = bytes.length;
		StringBuilder buf = new StringBuilder(len * 2);
		// 把密文转换成十六进制的字符串形式
		for (byte aByte : bytes) {
			buf.append(HEX_DIGITS[(aByte >> 4) & 0x0f]);
			buf.append(HEX_DIGITS[aByte & 0x0f]);
		}
		return buf.toString();
	}

	public static String encode(String str) {
		if (str == null) {
			return null;
		}
		try {
			MessageDigest messageDigest = MessageDigest.getInstance("SHA1");
			messageDigest.update(str.getBytes());
			return getFormattedText(messageDigest.digest());
		} catch (Exception e) {
			throw new RuntimeException("sha加密生成签名失败");
		}
	}

}
